Keywords:
Cold stress, Dehydrin, Frost tolerance, Phytohormones, WheatAbstract:
Hormonal changes accompanying the cold stress (4 ◦C) response that are related to the level of frost
tolerance (FT; measured as LT50) and the content of the most abundant dehydrin, WCS120, were compared
in the leaves and crowns of the winter wheat (Triticum aestivum L.) cv. Samanta and the spring
wheat cv. Sandra. The characteristic feature of the alarm phase (1 day) response was a rapid elevation of
abscisic acid (ABA) and an increase of protective proteins (dehydrin WCS120). This response was faster
and stronger in winter wheat, where it coincided with the downregulation of bioactive cytokinins and
auxin as well as enhanced deactivation of gibberellins, indicating rapid suppression of growth. Next, the
ethylene precursor aminocyclopropane carboxylic acid was quickly upregulated. After 3–7 days of cold
exposure, plant adaptation to the low temperature was correlated with a decrease in ABA and elevation of
growth-promoting hormones (cytokinins, auxin and gibberellins). The content of other stress hormones,
i.e., salicylic acid and jasmonic acid, also began to increase. After prolonged cold exposure (21 days), a
resistance phase occurred. The winter cultivar exhibited substantially enhanced FT, which was associated
with a decline in bioactive cytokinins and auxin. The inability of the spring cultivar to further increase
its FT was correlated with maintenance of a relatively higher cytokinin and auxin content, which was
achieved during the acclimation period.DOI:Fulltext: contact IEB authorsIEB authors:Petre I. Dobrev, Alena Gaudinová, Václav Motyka, Ondřej Novák, Bedřich Pešek, Alena Trávníčková, Radomíra Vanková